A major abortion clinic described as a "house of horrors" in Muskegon, Mich., has been closed down after a pro-life group helped investigators look into alleged illegal practices at the facility.

"We are happy to announce that the closure of Women's Medical Services is the twenty-fourth abortion clinic to close in 2012," Troy Newman, President of Operation Rescue and Pro-Life Nation, said in a statement on Thursday.

Cheryl Sullenger, Senior Policy Adviser at Operation Rescue, explained to The Christian Post that the clinic in question is the Women's Medical Services in Muskegon run by Dr. Robert Alexander, an abortionist who has had his medical license revoked twice in the 1990s, but regained it after an appeal. The Muskegon Fire Department officially posted closure notices earlier this week outside the clinic.

"We had information that his abortion clinic was a filthy 'house of horrors' where he engaged in practices that violated the standard of care, to say the least," Sullenger shared with CP. "We reported him to the authorities. Because of the ongoing nature of the investigations, we are not at liberty to say much more for now, however, we do not think this will be the last development in the case."

The policy adviser noted that because Operation Rescue wants the case to proceed without impairment, the group cannot reveal details of what was going on behind closed doors – but Sullenger said that she is "thankful that this dangerous abortion mill is closed," and is confident that Dr. Alexander will never be able to open it again.

Although Operation Rescue has reported the alleged unsafe practices at Women's Medical Services to authorities, local news reports indicate that the facility was shutdown after police received a call about a possible break-in. Officers reportedly found a broken rear-end window, and while they found no evidence of robbery inside the clinic, they noted several possible building and health code violations – details of which still remain under wraps.

An unnamed employee at Women's Medical Services is said to have told WZZM that staff found blood splattered around the facility and were "devastated" at the incident.

"This is one less abortion clinic that can prey upon vulnerable women and their pre-born babies, and for that, we are thankful," Operation Rescue's Newman added in the press release.

The organization says that it received photographs confirming the closure, which show the clinic's doors boarded up with plywood panels. According to Operation Rescue, abortion clinics in America are closing up at a rate of two per month, and that today there are currently 660 places providing the procedure that are still active – a drastic decline from 1991, when 2,176 clinics were active.

"We look forward to the day when all abortion sites have been shut down and the pre-born baby is once again protected by law," the organization says.

In its Year-end review, the pro-life group published its top 10 victories of 2012, which include a number of other major abortion clinics the group claims to have helped close. Operation Rescue, founded in 1986, is currently trying to close the last remaining abortion clinic in Missouri, the St. Louis Planned Parenthood center, in its goal to shut down all clinics nationwide on a state-by-state basis.